Fireplace damper won't shut

[mm]

Hi! I have a steel fireplace, 29 years old, with a round metal chimney and a metal damper. I've used it may be 50 times. Now I'm having trouble shutting the damper.

And to a lesser extent, opening it. I can open it if I push harder than I used to.

And I can shut it if I put my hand up inside a foot so that I can pull the rod to the side while I'm pulling it down.

What can I do to make this work pretty smoothly, like it had before?

I had my furnace chimney cleaned a few years ago, and the sweep didn't even suggest cleaning the fireplace chimney, and I didn't remember until he was gone. They are the same size also!

[mm]

I forgot to say that I looked up at the damper and it's a round metal disk with a pivot rod accross it in the middle, and on the side that goes UP when the damper is open, about half way across that half is attached a long rod that goes down the fireplace opening. That's the control. Because the damper opens all the way to the point that the round metal disk is vertical, pulling down doesn't cause much lateral force, so the disk doesn't rotate on its pivot and it doesn't move at all. If it were a lot bigger than 10 or 12 inches and I could get in there, maybe I'd just put in something that kept the damper from getting totally vertical, but I think it was built the way it is now, so I think there's a better solution anyhow.

[k]

Ask at a stove shop near you. I think they label themselves 'hearth dealers' these days. They should have a high-temp lubricant that will help you out for just a few bucks.

Keith